After nicotine is excreted it is easily resorbed from the bladder when urine has low acidity and poorly when acidity is high. Presumably, if nicotine level of the blood governs, in part tendency to smoke, those with highly acid urine may tend to smoke more heavily (inhalation, butt length, and/or number of cigarettes) than people with urine of low acidity. Moreover, such a relationship should be stronger, it is hypothesized, among heavy smokers than among light. It is proposed to test these hypotheses.